Just a quick update… I received the piston ring yesterday in the mail. After a few choirs, it was down to the hobby workshop and started in on the YS. I removed the motor from the Rave and stripped the YS down to its case. The sleeve has some marks / scratches that is only visible, I’ll microscope (30x eye loop) the sleeve to verify this.

The piston isn’t pretty, half of the top section, above the ring, is shattered. I believe it was from switching from rich / lean / rich condition....